Cork-composition slab and method of making same



March 17, 1925.

c. E. M MANUS CORK- COMPOSITION SLAB AND METHOD OF MAKING SAME Filed July 6, 1922 Ky L INVENTOR ATTORNEY. Y

Patented Mar. 17, I25. I

omrso STATES PATENT CHARLES E. MCMANUS, OF N EWYORK, N. Y;

CORK-COMPOSITION SLAB AND METHOD OF MAKING SAME.

Application filed July 6,

To all whom it may concern:

Be it known that I, CrrAnit-Es E. MCMANUS,

a eitizenof the United States, residing at the borough of Manhattan, in the city, county, and State of New York, have invented certain new and useful Improvements in Cork-Composition Slabs and Methods of Making Same, of which the following is a specification, reference being had therein to the accompanying drawings, which form a part thereof.

My invention relates to composition cork slabs consisting of a homogeneous mass of small particles of cork united by means of a thin film of suitable adhesive, binder or glue upon each particle of cork, and to the method or art of forming such slabs in a manner to ensure substantially uniform density and resiliency throughout the entire slab.

Composition cork slabs or sheets'have been heretofore,manufactured with the use of various difi'erent binders, adhesives or glues, it having been a common practice to form said slabs in a mould, the entire volume of granular cork required to make a slab of the desired dimensions, after being mixed with the binder, adhesive or glue, being charged into the mould in one batch and subjected to very heavy pressure, usually by means of an hydraulic press, to secure compactness anddensity in the material of the slab. In some instances rollers have been used instead ofan hydraulic press, but irrespective of the mechanisms used, the efiect has always been to compact the cork gran-' -ules by mechanical means'and by surface pressure applied to the largest area of the slab and throughout substantially theentire area [thereof at one'and the same time. y

In the handling of small cork particles having but a thin coating. of binder, adhesive or glue, it is practically impossible,

by the old methods above referred to, to secure uniform density in the product by the application of mechanicalpressure thereto, by reason of the elasticity inherent to the cork particles and the lack of fluidity in the large mass of cork being compressed.

Cork slabs ofthe character herein referredto are commonly used in making packing gaskets for various purposes, the slabs being sliced into sheets of the desired thickness. It is absolutely essential that such gaskets have no material openings thereelasticity throughout.

A composition cork slab embodying my invention is formed of graded cork gran ules, each having a thin surface coating of suitable binder, adhesive or glue, which when set is sufliciently flexible to impart" flexibility to the entire slab or to sheets sliced therefrom, the slab being of substantially uniform density and elasticity throughout, and characterized b the absence of any superficial or conceale voids. The flexibility inherent to the cork, and to the binder, adhesive or glue, will permit the slicing of the slab without likelihood of local ,disintegration in any portion of thematerial of the slab.

In the production of slabs embodying my invention, I employ a novel method or art by means of which the binder coated cork particles are progressively packed in a mould under conditions which will compact the mass of particles of cork while the binder, adhesive or glue has no adhesive properties. the filling of the mould being accomplished under light pressure as com pared with the pressure developed by anhydraulic press or a roller of the type hereinbefore referred to. Merely suflicient pressure is used to ensure an approximate uniform compactness or density throughout the entire mass of cork particles with which the mould is ultimately charged, which cannot be secured by a light tamping action.

The pressure exerted must also be sufliciently great to overcome the frictional resistance between the cork granules or particlesof ing slabs having top and bottom areasmany times greater than the cross-sectional area of the slab.

I I have found it essential to deliver the binder coated cork granules through a narrow open end of the mould correspending with the cross-sectional area of the slab, it being essential that cork particles of a considerable thickness be subjected to each compressing action in order that a fairly uniform compaction of the diderent charges may be attained when filling the mould.

After a mould has been completely filled readjustment since enlargement of the mass in the manner described, the fillingopening is closed by means of a plug of a. depth to engage the cork composition within the mould, and the mould is then subjected to a temperature sufficiently high to set or vuljustment of the cork granules as will ensure uniform density and elasticity throughout the entire mass,

this expansion or tendency toward expansion developing a pressure,

within the mould which will cause, such is prevented by the mould.

The invention consists primarily in the method or art of making cork composition slabs wherein a succession of substantially uniform charges of cork composition consisting of cork granules each having a thin surface coating of an adhesive, are delivered through an open edge of a mould having the form of a parallelepiped, each charge being subjected to substantlally' uniform pressure throughout an area substantially corresponding with the cross-sectional area of the mould, confining said composition cork within the mould without applying pressure thereto by a non-yieldable member contacting with the cork composition, subjecting said mould and its contained cork composition to an elevated temperature, whereby said adhesive will be made plastic and the tendency of the cork composition to expand, will cause a readjustment of the cork granules within the mould to secure uniform density in the slab, and thereafter seasoningthe slab under normal temperature; and in other novel steps and practices, and a cork slab produced by the above method or art, all as hereinafter set forth and described, and more particularly pointed out in the claims hereto appended.

Referring to the drawings,

Fig. 1 is a diagrammatic view illustrating the method or art of my invention;

Fig. 2 is a detail view of a mould used in this method or art; and

Fig. 3 is a perspective view of the finished product.

7 Like letters refer to like parts throughout the several views.

In the practice of the method or art of my invention, I employ a mould a in the form of a parallelepiped, which may have any desired dimensions so long as the width or cross-sectional area of the opening within the mould is materially less than the length .or depth of the mould so as to present much larger surface areas to the finshed product than the cross-sectional area or edge thereof.

or glue,

'in the baker, vulcanizer or oven,

Three edges of the mould a are closed, the remaininw edge remaining open to permit the introduction of cork composition thereinto. Into this mould, 'I successively deliver a plurality of charges of a cork composition consisting of granular cork, each granule of which has a thin surface coating of a binder, adhesive or glue, which becomes adhesive only when subjected to heat and when set will retain sufiicient flexibility to avoid the presence of brittleness in the finished product. A number of different binders, adhesives or glues may be used, one well known adhesive being a mixture of gelatine, glyc-' erine and a member of the aldehyde group, sufficient water being added to give the desired fluidity to the binder, adhesive or glue so that it may be readily worked with the granular cork while avoiding the presence of moisture in quantity sufiicient to interfere with a proper conditioning of the binder, adhesive or glue, or a loss of time in the seasoning of the product during which the ultimate setting of the binder, adhesive or glue.

occurs.

The'binder, adhesive orglue described has the further adyantage that, when set, it be comes a sort of synthetic rubber, possessing elasticity, thus not only securing a resilient product throughout, but facilitating the slicing of the slabs into sheets of the desired thickness.

As each charge is introduced into the mould a through the open edge thereof, it'is subjected to a' continuing pressure for a sufficient interval to mechanically compact the composition of the charge, thus reducing the number and size of the voids as much as is practicable, although uniform density of the cork composition in the mould is not assured by the mechanical compaction of each charge. When a mould has been completely filled, the open edge thereof is closed by a plug 6, the inner end of which contacts with the cork composition in the mould.

In order to prevent voids in excess of thosewhich can be closed by the binder, adhesive I preferably use cork relatively different dimensions. graded cork granules or particles,

granules .of

est of'which are but little larger than cork dust, I secure avery much betterproduct in every way. After a mould has been filled'and the plug inserted as described, the mould is passe through a baker, vulcanizer or oven maintained at an elevated temperature, the temperature employed varying with the binder, adhesive or glue used, care "being necessary to prevent the temperature reaching a point where it will scorgh thebinder, adhesive or glue, but-being maintained as'near to the scorching temperature as possible. While the binder,

adhesive or glue is brought to a plastic,

lation to each other. and substantially uniform density and elasticity throughout the ent-ire mass.

After being subjected to heat for the desired interval, which will vary according to the binder, adhesive or glue used, the mould is removed from the baker, vulcanizer or oven, and immediately subjected to normal temperatures, the drop of temperature having the effect of instantly setting that portion of the binder, adhesive or glue which is closely adjacent the surface of the material in the mould, although a much longer interval is required to thoroughly dry and set all of the binder, adhesive or glue throughout the mass. v

- The large surface areas contacting with the inner walls of the mould will, notwithstanding the slight shrinkage of the cork composition when partially cooled, prevent the forcing of the slab edgewise thereof from the mould, owing to the frictional resistaneeor suction which must be overcome. To meet this condition, I withdraw the entire slab from the mould flatwise thereof, said mould being provided with a removable side as c for facilitating this step.

After the slab has been withdrawn from the mould, it is exposed to normal tempera ture for a considerable interval to permit the completion of the seasoning of the slab necessary to thoroughly dry out the moisture of the binder, adhesive or glue, although the glycerinc will preserve the flexibility therein even after complete seasoning of thesla-b. Forty-eight hours is ordinarily ample time for the seasoning step, although this interval may be reduced before cutting the slabs into sheets as described.

In the accompanying drawings, 1 have indicated conventionally at ol a measuring device for introducing a charge of the cork composition to within the mould a, and a plunger 6 which, with one stroke thereof, will compact the charge.

lVhile the mechanisms employed are immaterial to my invention, it is apparent that a succession of measuring devices a? and plungers e may be used to secure the desired capacity in a plant for producing the productby the method or art of my invention.

The product of the method or art above described is a slab'of very much smaller cross-sectional area than the top surface area, which top area is substantially rectangular, said slab being composed of cork granules united by a thin surface stratum of a flexible binder, adhesive or glue. The slab in its entirety is of substantially uniform density and elasticity throughout and substantially free from surface or concealedvoids.

The dimensions of the aforesaidslab will correspond with those of the cavity of the mould, the opening in the mould through which the charges of cork composition are delivered corresponding in dimensions with the thickness of the slab which will be a smaller cross-sectional area of the slab or of the mould cavity, corresponding With one edge of the completed slab. Throughout the specification and claims, the term edge is used as designating this small cross-sectional area either ip the mould or in the completed slab, the top and bottom of the slab referring to the surfaces of the slab or the sides of the mould having the largest dimensions.

An essentia-Lcharacteristic of the invention is the introduction of the charges of cork composition through an edge of the mould, thus limiting the area subjected to mechanical compression or compaction and consequently limiting each charge to a volume sufliciently small to avoid the interference with. compression or compaction thereof,-by frictional resistance atthe' walls of the mould cavity, and preventing a localized compression resulting from this friction or variance in the quantity of the composiw tion in different portions of each charge.

'Having described the invention, what it claim as new and desire to have protected by Letters Patent, isrcomposition slabs wherein a succession of substantially uniform charges of cork composition consisting of cork granules .each' having a thin surface coating ofan adhesive, are dellvered through an open edge of a 1. The method or'art of making cork.

llt

mould having the form of a parallelepiped,

the; width or cross-sectional area of the mould opening being materially less than the length or depth thereof, said-open edge being coincident with the cross-sectional area of said mould opening, each charge being subjected to substantially uniform pressure throughout an area substantially corresponding with the cross-sectional area of the mould, confiningsaid composition cork within the mould without applying prespand, will cause a readjustment of the cork mould opening being materially less than the length or depth thereof, said open edge being coincident with the cross-sectional area of said mould opening, each charge belng sub ected to substantially uniform pressure throughout an area substantially cor responding with the cross-sectional area of the mould, confining said within the mould without applying pressure thereto by a nonyieldable member contacting with the cork composition, subjecting said mould and its contained cork composition to an elevated temperature,'whereby said adhesive will be made plastic and the tendency of the cork composition to expand, will cause a readjustment of the cork granules within the mould to secure uniform density in the slab, drawing the slab through a side of the mould corresponding with the surface of the slab having the larger dimensions, after removing the mould from the high temperature zone, and thereafter seasoning the slab under normal temperature.

3. The method or art 'of making cork composition slabs wherein a succession of substantially uniform charges of cork composition consisting ules, difl'erent portions of which are graded as to size, said granules each having a thin surface coating of an adhesive, are delivered -a opening,

through an open edge of a mould having the form of a parallele iped, the width or crosssectional area of t e -mould opening being the length or depth thereof, said open edge being coincident with the cross-sectional area of said mould each charge being subjected to substantially uniform pressure throughout an area substantially corresponding with the cross-sectional area of the mould, confining said 'composition cork within the mould' without applying pressure thereto by a nonyieldable member contacting with the cork composition, subjecting said mould and its contained cork composition to an elevated temperature, whereby said adhesive will be made plastic and the tendency of the cork composition to expand, will cause a read- I composition cork of a mass of cork gran-' relatively much less justment of the cork granules within the mould to secure uniform density in the slab, and thereafter seasoning the slab under normal temperature.

4. The method composition slabs wherein a succession o substantially uniform charges of cork composition consisting of a mass of cork granules, different portionsof which are graded as to size, said granules each'having a thin surface coating of an adhesive, are delivered through an open edge of a mould having the or art of making cork.

form of a palallelepiped, the width or crosssectional area of the mould opening being materially less than the length or depth thereof, said open edge being coincident with the cross-sectional area of said mould opening, each charge being subjected to substantially uniform pressure throughout an area substantially corresponding with the cross-sectional area of the mould, confining said composition cork within the mould without applying pressure thereto by a nonyieldable member contacting with the cork composition, subjecting said mould and its contained cork composition to an elevated temperature, whereby said adhesive will be made plastic and the tendency of the cork composition to expand, will cause a readjustment of the cork granules within the mould to secure uniform density in the slab, drawing the slab through a side of the mould corresponding with the surface of the slab having the larger dimensions, after removing the mould from the high temperature zone, and thereafter seasoning the slab under normal temperature.

5. A, cork composition slab composed of a mass of cork granules bonded together by a thin surface coating of a flexible adhesive, the cross-sectional area of said slab being f than the top area there- 0 6. A cork composition slab composed of a mass of cork granules, different portions of which are graded as to size, said granules being bonded together by a thin surface coating of a flexible adhesive, the cross-sectional area of said slab being relatively much less than the to area thereof.

In witness whereof I havehereunto affixed iny signature, in the presence of two subscribing Witnesses, this 23rd day of June.

CHARLES E. MCMANUS.

Witnesses:

FRIEDA KOEHLER, SOPHIE M. BAEDER. 

